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T
- the required bean typepublic interface Instance<T>
Allows the application to dynamically obtain instances of beans with a specified combination of required type and qualifiers.
In certain situations, injection is not the most convenient way to obtain a contextual reference. For example, it may not be used when:
In these situations, an instance of the Instance may be injected:
@Inject Instance<PaymentProcessor> paymentProcessor;
Any combination of qualifiers may be specified at the injection point:
@Inject @PayBy(CHEQUE) Instance<PaymentProcessor> chequePaymentProcessor;
Or, the @Any
qualifier may
be used, allowing the application to specify qualifiers dynamically:
@Inject @Any Instance<PaymentProcessor> anyPaymentProcessor;
Finally, the @New
qualifier
may be used, allowing the application to obtain a
@New
qualified bean:
@Inject @New(ChequePaymentProcessor.class) Instance<PaymentProcessor> chequePaymentProcessor;
For an injected Instance:
The inherited Provider.get()
method returns a
contextual references for the unique bean that matches the required
type and required qualifiers and is eligible for injection into the
class into which the parent Instance was injected, or throws
an UnsatisfiedResolutionException
or
AmbiguousResolutionException
.
PaymentProcessor pp = chequePaymentProcessor.get();
The inherited Iterable.iterator()
method returns
an iterator over contextual references for beans that match the required
type and required qualifiers and are eligible for injection into the class
into which the parent Instance was injected.
for (PaymentProcessor pp: anyPaymentProcessor) pp.test();
Provider.get()
,
Iterable.iterator()
,
AnnotationLiteral
,
TypeLiteral
Method Summary | ||
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boolean |
isAmbiguous()
Determines if there is more than one bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent Instance was injected. |
|
boolean |
isUnsatisfied()
Determines if there is no bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent Instance was injected. |
|
Instance<T> |
select(java.lang.annotation.Annotation... qualifiers)
Obtains a child Instance for the given additional required qualifiers. |
|
|
select(java.lang.Class<U> subtype,
java.lang.annotation.Annotation... qualifiers)
Obtains a child Instance for the given required type and additional required qualifiers. |
|
|
select(TypeLiteral<U> subtype,
java.lang.annotation.Annotation... qualifiers)
Obtains a child Instance for the given required type and additional required qualifiers. |
Methods inherited from interface java.lang.Iterable |
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iterator |
Methods inherited from interface javax.inject.Provider |
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get |
Method Detail |
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Instance<T> select(java.lang.annotation.Annotation... qualifiers)
Obtains a child Instance for the given additional required qualifiers.
qualifiers
- the additional required qualifiers
java.lang.IllegalArgumentException
- if passed two instances of the
same qualifier type, or an instance of an annotation that is not
a qualifier type<U extends T> Instance<U> select(java.lang.Class<U> subtype, java.lang.annotation.Annotation... qualifiers)
Obtains a child Instance for the given required type and additional required qualifiers.
U
- the required typesubtype
- a Class
representing the required typequalifiers
- the additional required qualifiers
java.lang.IllegalArgumentException
- if passed two instances of the
same qualifier type, or an instance of an annotation that is not
a qualifier type<U extends T> Instance<U> select(TypeLiteral<U> subtype, java.lang.annotation.Annotation... qualifiers)
Obtains a child Instance for the given required type and additional required qualifiers.
U
- the required typesubtype
- a TypeLiteral
representing the required typequalifiers
- the additional required qualifiers
java.lang.IllegalArgumentException
- if passed two instances of the
same qualifier type, or an instance of an annotation that is not
a qualifier typeboolean isUnsatisfied()
Determines if there is no bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent Instance was injected.
boolean isAmbiguous()
Determines if there is more than one bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent Instance was injected.
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